Thio-indoxyl derivative and process of making same.



UNITED STATES IATENT OFFICE.

PAUL FRIEDLAENDER, OF VIENNA, AUSTRIA-HUNGARY, ASSIGNOR TO THE FIRM OF KALLE AND COMPANY AKTIENGESELLSOHAFT, OF BIEBRICH,

GERMANY.

THlO-INDOXYL DERIVATIVE AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Lratented April 16, 1907.

Application filed N em 6, 1905. Serial No- 287.727- (Specimena) To an whom it may concern.- ta jBe it known that I, PAUL FRIEDLAENDER,

doctor of philosophy, a subject of the Em- SH (1) 6H4 COOH (2),

phenyl-thio-glycolortho-carboxylic acid,

0 SCH2COOH (1) coon (2),

S au C-OOOH (I).

O OH,

which on being heated alone or in the presence of dilute acids evolves carbonic acid, with the formation of another new compound having probably the following constitution:

(J OH.

I designate the compound I as thio-indoxyl-carboxylic acid and (in accordance with this nomenclature) compound II as thio-indoxyl. The products to which this application refers are therefore thio-indoxyl derivatives of the following general constitution:

s\ 06H cx 4 0 0x,

in which X serves to denote either acarboxylic group or ahydrogen atom.

The new compounds have the following properties: Thio-indoxyl-carboxylic acid is diflicultly soluble in cold Water. It is, however, readily dissolved by dilute alkalies, with the formation of the corresponding salts. The thio-indoxyl-carboxylic acid can by acidifying the alkali solution be again precipitated therefrom as a yellowish-white crystalline mass, which gradually becomes red under the action of air and light. If asuspension of this acid in water be heated, carbon dioxid is evolved and thio-indoxyl is formed. The separation of the carbon dioxid is greatly facilitated by the action of acids- If this acid be heated some considerable time by itself at a high temperature, the carbon dioxid is given off and thioindoxyl formed, which distils over with aqueous vapors and has an odor similar to that of alpha-naphthol and melts in the pure state at 73 centigrade. Both compounds are distinguished by the property to be transformed into a most valuable redsulfur coloring-matter by a treatment with air or by the action of other oxidizing agents.

The following examples will illustrate how the invention may be carried out; but I do not bind myself to the precise modes of operation nor to the precise proportions stated, the said examples being merely some modes of carrying out the process whose general characteristics have been hereinbefore stated. Example I: Twenty kilograms of phenylthio-glycol-ortho-carboxylic acid are stirred with a little water and introduced at 100 centigrade into a mixture of one hundred kilograms of caustic soda and twenty liters of water. The temperature is then. raised to IOC from 170 to 180 centigrade, and that temperature is maintained for about an hour. The melt contains the thio-indoxyl-carboxylic acid in the form of its sodium salt. To isolate the acid, the cooled melt is dissolved in water and (taking care to avoid any appreciable rise of temperature) slightly acidilied by means of mineral acid, filtered, and pressed. The thio-indoxyl-carboxylic acid may also be oxidized directly into a coloringmatter without previous isolation.

Example 11: 1t is also possible to convert the phenyl-thio-glycol-ortho-carboxylic acid into the tnio-indoxyl derivative by mixing it intimately with more than two molecular proportions of dry caustic soda and then heating it to a temperature varying between 160 and 250 centigrade. A mixture consisting, of twenty kilograms of phenyl-thioglycol-ortho-carboxylic acid and sixteen kilograms of caustic soda is heated for an hour in an oven to a temperature of 250 centigrade. After cooling the f product is dissolved in water and acidified with mineral acid. The thio-indoxyl-carboxylic acid is thereby separated as a white precipitate. If on acidifying the temperature is allowed to rise, carbon dioxid is partly given off and a corresponding quantity of thio-indoxyl is obtairclied along with the thio-indoxyl-carboxylic ac1 Example III: The action of other agents can also cause the condensation of the phenylthioglycol-ortho-carboxylic acid into thio-indoxyl-carboxylic acid. One part byv weight of the phenyl-thio-glycol-ortho-carboxylic acid is mixed with aboutfive parts, by weight, of acetic anhydrid and a little sodium acetate, and the mixture is heated for a short time to from 50 to centigrade. The condensation takes place smoothly and rapidly. If heated to a higher temperature, carbon dioxid is evolved and thio-indoxyl is obtained along with the thio-indoxyl-carboxylic acid, and when the heatin is carried on for a sufliciently long time on y thio-indoxyl is obtained. In the above examples instead of phenyl-thio-glycol-ortho-carboxy lic acid its acid or neutral esters may be used, in which case the condensation into thio-indoxyl-carboxylic acid is advantageously carried out by means of sodium alcoholate, or alcoholic caustic soda.

Example IV: Seventy-five kilograms of a paste containing twenty per cent. of thioindoxyl-carboxylic acid are diluted with two hundred liters of water and mixed with ten kilograms of hydrochloric acid. The mixture is heated in a vessel provided with a r'efiux condenser until the whole mass is melted. The thio-indoxyl-carboxylic acid is converted into thio-indoxyl with evolution of carbon dioxid. After cooling the thio-indoxyl is filtered and washed.

Example V: Seventy-five kilograms of a paste containing twenty per cent. of thioindoxyl-carboxylic acid are diluted with two hundred liters of water in a suitable distilling vessel. The mixture is heated 'to centigrade, and a current of steam is passed through it. Carbon dioxid is evolved, and the thio-indoxyl-carboxylic acid is converted into thio-indoxyl, which distils .oif with the aqueous vapors.

Example VI: Fifteen kilograms of finelypulverized phenyl thio glycol ortho car boxylic acid are heated for about two hours in a suitable vessel. Aqueous vapor is first given 0H, and afterward carbon dioxid is evolved. I The thio-indoxyl obtained can be purified by distillation with aqueous vapors or by any other suitable method.

In producing thio-indoxyl its property of oxidizing readily in contact with air or 0x1- dizing agents should in all cases be taken into account.

The above-described thio-indoxyl derivatives are of high technical value-for instance, for the production of a new red sulfur containing coloring-mattercf. my application for- Letters Patent of the same .date.

Now what I claim is 1. A process for the preparation of thioindoXyl-carboxylic acid by reacting on phenyl-thio-glycol-ortho-carboxylic acid with deyhdrating agents.

2. A process for the formation of thio-indoxiyl by heating thio-indoxyl-carboxylic aci 3. A process for the formation of thio-in- ,doxyl by heating thio-indoxyl-carboxylic acid with the addition of acids.

., 4. As new products of manufacture thioindoxyl derivatives obtainable as hereinbefore described, being diflicultly soluble in water, easily soluble in alkalies and which are transformed into red dyes containing sulfur on treatment with oxidizing agents.

5. As'a new product, the thio-indoxylcarboxylic acid, obtainable by treating phenyl thio glycol ortho carboxylic acid with deyhdrating agents, being a colorless crystalline bodydillicultly soluble in water easily soluble in alkalies, givin off carbon dioxid on heating, and which y treatment with oxidizing agents is transformed into a red dye contamlng sulfur.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. j

PAUL FRIEDLAENDER.

Witnesses:

IGNAZ ROSENBERG, JEAN GRUND.

ICC 

